The searching strategies and keywords included “preimplantation genetic diagnosis”, “PGD”, “Huntington”, “neurodegenerative”, “spinocerebellar ataxia”, “spinal muscular atrophy”, “SMA”, “prion”, “familial amyloidosis”, “Charcot–Marie–Tooth”, and “CMT”. This evidence concerns the gene SMN1 and proximal spinal muscular atrophy.